What happens if you give your baby full-strength apple juice?

My 6.5 month old had a check up yesterday and my doctor told me it's ok to start giving her small amounts of juice. So today I bought the Gerber apple juice and I gave it to her in her sippy cup. In my excitement of giving her something new, I forgot to dilute the juice (half juice, half water). She drank all of it before I realized. What happens if you don't dilute it?